Objective: To describe the perinatal and neonatal outcomes for fetuses with posterior fossa (PF) anomalies - mega-cisterna magna (MCM), persistent Blake's pouch (PBP) or the Dandy-Walker continuum (DWC) - using a new classification. Methods: 46 cases with PF anomaly diagnosed on ultrasound (US) between 16 and 28 weeks' gestation were included. The images were reviewed and classified as one of the following: MCM, PBP or DWC. Outcomes were obtained from patient records. Results: 30 cases with DWC, 6 with MCM, and 10 with PBP were identified. Associated anomalies were present in all groups, but more frequent in DWC. Agenesis of the corpus callosum and ventriculomegaly were more common in DWC than in MCM or PBP. Only fetuses with DWC were found to have chromosomal abnormalities. Perinatal outcomes differed significantly, with terminations of pregnancy more frequent in DWC. In the immediate postnatal period, infants with DWC had worse outcomes than those with MCM and PBP. Across all groups, those with associated anomalies had worse outcomes than those with an isolated PF anomaly. Conclusion: Infants antenatally diagnosed with DWC had worse perinatal and short-term neonatal outcomes than those with MCM or PBP. Those with associated anomalies had uniformly poorer outcomes than those with isolated anomalies.

Objectives:To study the correlation of the gestational age and fetal cerebellar vermis measured by using virtual organ computer aided analysis (VOCAL) of three-dimensional ultrasound. Methods: 540 normal fetuses at 18 ∼ 35 gestation weeks were examined with trans-abdominal two-dimensional ultrasound (TAS) and trans-abdominal three-dimensional sonography (3D US). Normal growth charts of the fetal cerebellar vermis were established by measuring its area on the mid-sagittal plane and volume by VOCAL. Results: Fetal cerebellar vermis volume was positively correlated with gestational age (r = 0.86, P < 0.05). Conclusions:The fetal cerebellar vermis volume could be measured by virtual organ computer aided analysis. The fetal cerebellum volume changed with the gestational age. Measurement of fetal cerebellar volume by VOCAL is able to be a reliability index to evaluate the development of vermis. P01.02Gender differences in the foetuses with mega cisterna magnaUltrasound Department, Qilu Hospital of Shandong University, Jinan, China Objectives: To observe the gender differences in the foetuses with mega cisterna magna. Methods: 75 Chinese singleton foetus between 22 and 38 weeks' gestational age with mega cisterna magna were included in this retrospective study. All of them were diagnosed by transabdominal sonography and confirmed by fetal magnetic resonance imaging (MRI) without other abnormities. The approval of the hospital ethical committee and informed consent of the mothers were obtained. All of the foetuses were followed up until delivery by physical and imaging examination. Determination of sex and the distribution of the foetuses according to sex were recorded. Results: In the 75 foetuses with mega cisterna magna, the number of male foetuses (57 male foetuses) was greater than female foetuses (18 female foetuses), and the proportion of the foetuses with mega cisterna magna in the male group was significantly higher than the foetuses in the female group (P < 0.05). Conclusions: Gender differences with mega cisterna magna exist in the foetuses. It would be reasonable to create different normal range values for male and female foetuses. Objectives: To assess the inter-observer reliability of fetal head biometry using archived 3D volumes and the impact of gestational age and presence of brain anomalies on examiners' performance. Methods: Seventy nine 3D volume datasets of fetal head were examined. 27 were normal, 52 had abnormalities. Offline analysis was done by 3 fetal medicine experts (E1, E2 &E2), all blinded to history and patient details. Measurements of the biparietal diameter (BPD), head circumference (HC), lateral ventricle (Vp), and transcerebellar diameter (TCD) were compared between examiners and to 2D measurements. Comparisons were made at 2 gestational age groups (≤ 22 and > 22 weeks) and in presence and absence of anomalies. P01.03 Results:The intra-class co-efficient showed a high level of measurement agreement between 3D examiners and 2D with values greater than 0.9 throughout. Bias was evident bet...

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